Operating valve of steam-engines



UNITED sTATEs PATENT oEEIoE.

SAMUEL \VILMOT, OF WATERTOW'N, CONNECTICUT.

PEEATG vALvE 0E STEAM-ENGINES.

specification or Letters Patent No. 16,668, dated February 17, 1857.

To :all whom it may concern:

Be it known that I, SAMUEL R. IVUMQT, of lVatertown, in the county ofLitchfield and State of Connecticut, formerly of the city, county andState of New York, have invented certain new and useful improvements insteam-engines which are particularly applicable to engines workingwithout cranks, crank-shafts, and fly-wheels, such as are employed fordriving saws, pumps, &c.; and I do hereby declare that the following isa full, clear, and exact description of my said invention, referencebeing had to the accompanying drawings, in which- Figure l represents aside view of a sawing apparatus driven by a direct acting steam enginehaving my improvements applied thereto, with the valve motion in theproper position when the piston rod is moving inward; Fig.-2 is a viewof the position of the traverse rod when the piston rod is movingoutward; Fig. 3 is a cross section at the line a' of Fig. l; Fig. 4 is alongitudinal section of a portion of the valvechest showing the throttlevalve, and Fig. 5 is a cross section of the same showing the steampassages.

In that class of engines in which the crank is dispensed with, and whichare frequent-ly employed for driving saws, pumps, and

blowing engines, it has long been a desid-A eratum to obtain someeliicient means of actuating the valves by a movement derived directly`from the piston rod.

The object of my invention is to eect this purpose in a simple manner,and it consists in a valve motion for actuating the valve or valves, bywhich the admission of steam to the steam cylinder of a steam engine,and the escape of steam therefrom are elfected and regulated, by amovement derived directly from the mot-ion of the piston rod. This valvemotion is composed mainly of a slide and of a traverse rod constructedand combined inV such manner, that during a portion of each stroke ofthe piston t-he slide ,imparts movement to the traverse rod so as toactuate the valve or valves, while during i another portion of thestroke the traverse rod sets the slide in a proper position to reactupon this rod during the succeeding Stroke of` the piston, and duringother portions of the stroke neither element of the combination actuatest-he other.

My improvement is represented in the accompanying drawing as attachedtoa portable sawing apparatus in which the saw A is attached to thecrosshead B of a direct acting' engine, whose steam cylinder C ispivoted to a heel block D and whose piston rod extends through ast-utiing box in the head of the steam cylinder and is at-tached to thecrosshead B. The butt of the cylinder is secured in a block or base F,in which the steam passages are situated, and which also contains thethrottle valve and steam valve; two of these passages terminate inpipes, the one a leading` to the boiler, and the other to the exhaustpipe. The other two passages lead to the steam cylinder, the one j beingconnected directly with the but-t thereof, and the other Ze with itshead through intervention of a side pipe c.

The steam valve in this instance is a fourway cock of the ordinarydescription, and the steam passages are arranged in such manner that aquarter of a revolution of the cone mI of the valve is required tochange the flow of steam and the exhaust from one end of the steamcylinder to the other. The valve stem G is prolonged in a directionparallel with the piston rod and its extremity is pivoted an arm Z thatprojects from the guide H, which guides the movement of the piston rod.That portion of the valve stem which is opposite the guide and parallelthereto is flattened; it is also twisted at two points f and g, to anextent equal to the angular motion of the cone of the valve` or aquarter of a revolution. This flattened portion of the valve stem formsa traverserod which is traversed by a slide I that is pivoted in an arm71., which projects from the orosshead B. This slide turns freely in itsarm to the extent of a quarter of a revolution, but its movement ineither direction beyond this extent is limited by two stops c and z',which alternately strike against the opposite shoulders of the arm h andthus stop the movement or partial revolution ot' the slide.

The stops are arranged in such manner that they permit the slide ltoturn upon the twisted portions of the traverse-rod when the slide ismoved in either direction from the extremities of the rod toward themiddle thereof; and that they will stop the turning of the slide in itsarm, and will consequently compel the twisted portion of the traverserod to turn -in the slide, and turn the cone of the valve, whenever theslide is moved in either direction from the middle of the traverse-rodtoward the extremities thereof. If therefore the piston and traverse rodbe s et as shown in Fig. l, with the slide in the position in which itis shown in Fig. 3, and the cone of the valve in the position shown inFig. 5, and if steam be admitted into the cylinder by opening thethrottle valve of the engine, the steam entering the cylinder andpressing upon the frontl face of the piston will drive the latter towardthe butt of the cylinder. As the piston approaches the end of its strokethe slide passes over the twisted portion f of the traverse rod, whichtends to cause the slide to turn upon it in the direc.- tion indicatedby the arrow in Fig. 3, but as at this time the stop z' is in contactwith the shoulder of the slide arm L, this stop prevents the turning ofthe slide I, and forces the traverse rod to turn in the slide, in adirection opposite to the arrow in Fig. 3, and thus turn the cone of thevalve. This movement of the valve changes the flow of steam from thehead of the cylinder to the butt thereof and puts the head of thecylinder in communication with the exhaust pipe. By this change, thesteam from the boiler is permitted to act upon the hinder face of thepiston and the latter is driven forward in the cylinder; as it movesforward the slide I is carried forward over the same twisted portion fof the traverse-rod, which now tends to turn the slide in the oppositedirection to the arrow in Fig. 3. As this tendency is not counteractedby the stops, the slide turns upon the traverse-rod without changingtheposition of the latter or that of the valve, and consequently withoutaffecting the iow of steam into the butt of the cylinder' or the exhaustof steam from the head thereof. By the time the slide has been carriedupon the straight portion of the traverse-rod extending between the twotwisted portions thereof, the other stop e has been brought in contactwith the shoulder of the slide arm 7L; so that when the slide is carriedover the twisted portion, y, of the traverse-rod, the tendency of thclatter to turn the slide is prevented by this stop; hence the traverserod is forced to turn in the slide and consequently to reverse theposition of the cone of the valve, and change the flow of steam from thebutt to the head of the cylinder; while by this same movement of thevalve, the butt of the cylinder is put in communication with the exhaustpipe. The change in the flow of the steam is followed by a reversal ofthe movement of the piston rod during which the slide I passes againover the second twisted portion g of the traverse rod withvout actingupon it; but acts as before upon the first twisted portion f thereof.

From the foregoing it will be seen that when the piston is moving fromthe center of the stroke toward either end thereof, the slide impartsmotion to the traverse-rod to .actuate the valve, because the turning ofthe slide at these periods by the action of the twisted portion of thetraverse rod is prevented by the stops e and When, however, the pistonis moving toward the center of the stroke from either end thereof, thestops do not prevent the turning of the slide, which is thus set in aproper position to react upon the traverse rod. And when the slide istraversing the straight portions of the traverse rod, the slide andtraverse rod do not act upon each other. As the slide turns thetraverse-rod and actuates the valve while the piston is approaching theend of its stroke, the steam is admitted in advance of the piston, andthe piston in its onward movement tends to force this steam to flow backto the boiler, or, as is commonly said, the valve has lead given to it.The amount of this lead is controlled by the position of the twistedportion of the traverse rod with respect to the range of motion of thepiston. The more nearly their position corresponds with the end of thestroke. the less will be. the lead, and vice versa. Hence it is in thepower of the constructor to adopt the lead to the work which the enginehas to perform, and to adjust it to the weight and velocity of thepiston and its accessories.

In the example I have described, the steam valve is a four-way cock, andthe traverserod is connected directly with the steam valve by forming itupon the prolongation of the valve stem. This mode of applying myinvention has been selected on account of its simplicity, but it isevident that my invention may be applied to operating steam valves ofother descriptions; thus for example it may be made to operate a shortslide valve, by connecting the stem of such a valve with an arm securedto the prolongation of the traverse rod; or it may be used in connectionwith puppet valves by connecting the stems of such valves with armsprojecting in opposite directions from the prolongation of thetraverse-rod, so that the valvesare raised and dropped alternately.These and other modifications may be made to adapt my improvements toparticular circumstances, and I propose to modify my invention as may benecessary to adapt it to the various circumstances under which it may beused.

That I claim as my invention and desire to secure by Letters Patent iswrIlhe valve motion herein described for operating the valves of steamengines and consisting essentially of a twisted t-raverse-rod of atraveling slide, and of the stops which limit the turning of the slide,or their equivalents combined together and operating substantially asherein set forth.

In testimony whereof I have hereunto subscribed my name.

SAMUEL R. WILMOT.

Vitnesses H. S. LINCOLN, F. H. FnN'roN,

